Rotary switch structure with saddleshaped insulator and two-legged contact brush



Dec. 28, 1965 KOUJI SEKI 3,226,495 ROTARY SWITCH STR URE WITH SADDLHAPED INSULATOR AND "1 LEGGED CT USH Filed 0 1963 United States Patent3,226,495 ROTARY SWITCH STRUCTURE WITH SADDLE- SHAPED INSULATOR ANDTWO-LEGGED CONTACT BRUSH Kouji Seki, Tokyo, Japan, assignor to FujitsuLimited, Kawasaki, Japan, a corporation of Japan Filed Oct. 2, 1963,Ser. No. 313,307 Claims priority, application Japan, Oct. 4, 1962,37/58,059 7 Claims. (Cl. 2tl0-11) My invention relates to rotaryswitches particularly for channel selection in miniaturized televisiontuners or other switching functions in high-frequency circuits.

Television tuners may be miniaturized by forming the stators of therotary channel selection switches from plate-mounted printed wiringwhich exhibits the required inductances and stray capacities betweenintermediate contact members, or by connecting the required inductancesand capacitances between contact members. Such rotary switches are thensuitable for switching the television radio-frequency circuits, themixer input and the local oscillator of a television set. However, theextent of miniaturization is still limited.

It is an object of my invention to provide a rotary switch which issmaller than those hitherto known and yet is capable of performing thefunction of larger devices.

More specifically, it is an object of my invention to provide a rotaryswitch with miniaturized brush contacts which selectively connect thecontact members of the stator.

Yet another object of the invention is to provide a miniaturized rotaryswitch having a contactor device which is smaller than hitherto knownbut yet assures secure contact of the rotary switch contactor parts.

To these ends and in accordance with a feature of my invention, I mounta shaft on the printed-wiring board holding the tuner circuits and printon the board a plurality of contact members circumferentially arrangedabout a contact ring. I then place a movable brush in such a position asto engage the contact ring and be engageable successively with therespective contact members, and I press the brush against the printedWiring ring and members with a resilient spring member mounted forrotation upon the shaft, while separating the spring member from thebrush with an insulating material.

These and other features will be pointed out in the claims. Otherobjects and advantages of the invention will become obvious from thefollowing detailed description when read in light of the accompanyingdrawing, wherein:

FIG. 1 is a perspective view of the printed rotary switch embodyingfeatures of the invention;

FIG. 2 is an exploded perspective view of a switch con tactor brush inFIG. 1;

FIG. 3 is a section taken along the lines III-III of FIG. 1; and

FIG. 4 is a section taken along the lines IV-IV of FIG. 3. cr'

In the drawings, two omega-shaped contactor brushes 1 each carry asaddle-shaped insulator 2 having retainer ends 2' fitting over the brushends. A circular sheet spring 3 presses downwardly upon the insulators 2and the brushes 1 by means of two diametrically arranged retainingmembers 3 extending radially therefrom and embracing the center portionof the saddle-shaped insulators 2 between the retaining ends 2'. In thismanner, lateral circular motion of the sheet spring 3 will move thebrushes in a circle. Downward pressure upon the spring 3 is applied by acollar 4' mounted on a shaft 4. The latter is keyed to the center of thesheet spring 3 and passes through a base plate 8 on which the shaft 4 ismounted by means of a bearing (not shown) which axially fixes the shaftbut permits it to rotate. Printed upon the top surface of plate 8 bynormal printed-wiring techniques are nine series connectedprinted-wiring-elements 5 arranged arcuately and coaxially about theshaft 4 and constituting the circuitry of a tuner. Contacts 6 extendingradially inward from the mutual joining points of elements 5 are alsoformed by printed-wiring techniques. An annular contact ring 7 isprinted by known means upon the upper surface of plate 8 so as to becoaxial with the shaft 4. The inner ends of respective contact points 6are spaced equally from the outer circumference of ring 7. As shown 'inthe drawings, the two legs of each brush 1 press respectively againstthe ring 7 and one contact point 6, thereby connecting them to eachother. Suitable printed connector leads 9 and 10 pass outwardly from oneend of the circular path formed by elements 5 and from the annular ring7.

The contactor brushes 1 connecting the contact points 6 with contactorring 7, the saddle-shaped insulator 2, and the sheet spring 3 areconstructed so that in operation both brush legs press against theirrespective printed surfaces 6, 7 with equal force.

In operation, an operator turns the shaft 4 by means of a knob (notshown) to select a channel. The shaft 4 turns the spring 3 whoseretainers 3' push against the insulator ends 2 so as to move theinsulators 2 and the brushes 1 along a circular path. The brushes thenconnect the adjacent points 6 with the ring 7 in consecutive order untilthe brush 1 contacts the particular contact 6 which corresponds totuning to the desired channel. If desired known means (not shown) can beprovided to temporarily hold the shaft 4 in discrete contact positions,each corresponding to one brush contacting one contact point 6 and hencecorresponding to the desired channel connection.

The resulting assembled device may be simply constructed out of fewparts and achieves a device which avoids fatigue and poor contact. Thisis particularly so because the spring member 3 is constituted of amaterial particularly suitable for providing spring pressure whereas thecontact brush 1 is comprised of another material particularly suitablefor brushes. The device is thus particularly suitable for overallminiaturization of high-frequency circuits.

The invention contemplates that the shaft 4 simultaneously actuates thedevice of FIG. 1 together with several devices identical with FIG. 1 andhaving boards 8 parallel to the board 8 of FIG. 1. Thus a single gangeddevice composed of several switches is available for simultaneouslyswitching various circuits such as the RF circuit and the localoscillator circuit as well as the converter circuit in a television orhigh-frequency tuning circuit.

While embodiments of the invention have been described in detail it willbe obvious to those skilled in the art that the invention may beotherwise practiced without departing from its spirit and scope.

I claim:

1. A rotary switch comprising an insulating base plate, a conductingcircular ring printed on said base plate, a plurality of conductingcontact means printed on said base plate and spaced circumferentiallyabout said ring, a plurality of circuit means printed on said baseplate, each of said circuit means connecting adjacent ones of saidcontact means and being arranged circumferentially about said ring, ashaft rotatably mounted on the base plate at the center of said ring, amovable contactor brush engaging said ring and engageable withsuccessive ones of said contact means, a saddle-shaped insulatorembracing said brush, resilient means rotatable with said shaft pressingsaid insulator and said brush against said base plate.

2. A rotary switch comprising an insulating base plate, a conductingcircular ring printed On said base plate, a plurality of conductingcontact means printed on said base plate and spaced circumferentiallyabout said ring, said contact means each being elongated and extendingtoward said ring, a plurality of circuit means printed on said baseplate, each of said circuit means connecting the outer radial ends ofadjacent ones of said contact means and being arranged circumferentiallyabout said ring, a shaft rotatably mounted on the base plate at thecenter of said ring, a movable contactor brush engaging said ring andengageable with successive ones of said contact means at the innerradial ends thereof, a saddleshaped insulator embracing said brush,resilient means rotatable with said shaft pressing said insulator andsaid brush against the base plate, said resilient means beingcircumferentially rigid so as to move said brush and insulatorcircularly in response to rotation of said shaft.

3. A rotary switch comprising an insulating base plate, a conductingring printed on said base plate, a plurality of conducting contactingmeans printed on said base plate and spaced circumferentially about saidring, a plurality of circuit means printed on said plate, each of saidcircuit means connecting different ones of said contact means and beingarranged circumferentially about said ring, a shaft rotatably mounted onthe base plate at the center of said ring, a pair of movable contactorbrushes engaging said ring and being each engageable with successiveones of said contact means on diametrically opposite sides of saidshaft, a pair of saddleshaped insulators each embracing a correspondingone of said brushes, a flat resilient plate secured to said shaft andhaving diametrically opposite retainer means pressing each of saidinsulators and each of said brushes against the base plate.

4. A rotary switch comprising an insulating base plate, a conductingring printed on said base plate, a plurality of conducting contactingmeans printed on said base plate and spaced circumferentially about saidring, a plurality of circuit means printed on said plate, each of saidcircuit means connecting different ones of said contact means and beingarranged circumferentially about said ring, a shaft rotatably mounted onthe base plate at the center of said ring, a plurality of movablecontactor brushes engaging said ring and being each engageable withsuccessive ones of said contact means, a plurality of saddleshapedinsulators each embracing a corresponding one of said brushes, a flatresilient plate secured to said shaft and having retainer means pressingeach of said insulators and each 'of said brushes against the baseplate. 5. A rotary switch comprising an insulating base plate, aconducting circular ring printed on said base plate, a plurality ofconducting contact means printed on said base plate and spacedcircumferentially about said ring,

a plurality of circuit means printed on said base plate, each of saidcircuit means connecting adjacent ones of said contact means and beingarranged circumferentially about said ring, a shaft rotatably mounted onthe base plate at the center of said ring, a plurality of movablecontactor brushes each having two legs and engaging said ring with oneleg and engageable with the other leg with successive ones of saidcontact means, a plurality of saddle-shaped insulators each embracing acorrespond ing one of said brushes about its upper and lateral surfacesand having end projections extending above the center portions thereof,a disc spring secured at its center to said shaft and having radiallyextending retainer members embracing the center portion of saidsaddle-shaped insulators between said end projections on each of saidinsulators so as to press said insulators and said brushes against saidbase plate.

6. A rotary switch comprising an insulating base plate, a conductingcircular ring printed on said base plate, a plurality ofangularly-spaced conducting contact means printed on said base plate andextending radially outward from locations spaced from said ring, aplurality of circuit means printed on said base plate, each of saidcircuit means connecting the outer radial ends of adjacent ones of saidcontact means and being arranged circumferentially about said ring, ashaft rotatably mounted on the base plate at the center of said ring, aplurality of movable contactor brushes each having two legs and engagingsaid ring with one leg and engageable with the other leg with successiveones of said contact means, a plurality of saddle-shaped insulators eachembracing a corresponding one of said brushes about its upper andlateral surfaces and having end projections extending above the centerportions. thereof, a disc spring secured at its center to said shaft andhaving radially extending retainer members embracing the center portionof said saddle-shaped insulators between said end projections on each ofsaid insulators so as to press said insulators and said brushes againstsaid base plate.

7. A rotary switch as claimed in claim 1, wherein said brush has twolegs and engages said ring with one leg and engages with the other legsuccessive ones of said contact means.

References Cited by the Examiner UNITED STATES PATENTS 1,624,374 4/ 1927SWoboda 200-11 2,805,291 9/ 1957 Eickhorst 200-11 2,847,523 8/1958 VanAmelsfort 20011 2,853,564 9/1958 Gahagan.

KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD A. GILHEANY, Examiner.

1. A ROTARY SWITCH COMPRISNG AN INSULATING BASE PLATE, A CONDUCTINGCIRCULAR RING PRINTED ON SAID BASE PLATE, A PLURALITY OF CONDUCTINGCONTACT MEANS PRINTED ON SAID BASE PLATE AND SPACED CIRCUMFERENTIALLYABOUT SAID RING, A PLURALITY OF CIRCUIT MEANS PRINTED ON SAID BASEPLATE, EACH OF SID CIRCUIT MEANS CONNECTING ADJACENT ONES OF SAIDCONTACT MEANS AND BEING ARRANGED CIRCUMFERENTIALLY ABOUT SAID RING, ASHAFT ROTATABLY MOUNTED ON THE BASE PLATE AT THE CENTER OF SAID RING, AMOVABLE CONTACTOR BRUSH ENGAGING SAID RING AND ENGAGEABLE WITHSUCCESSIVE ONES OF SAID CONTACT MEANS, A SADDLE-SHAPED INSULATOREMBRACING SAID BRUSH, RESILIENT MEANS ROTATABLE WITH SAID SHAFT PRESSINGSAID INSULATOR AND SAID BRUSH AGAINST SAID BASE PLATE.